Commit 9b54bf9d authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

kernel: add kcompat_sys_{f,}statfs64() 



Using this helper allows us to avoid the in-kernel calls to the
compat_sys_{f,}statfs64() sycalls, as are necessary for parameter
mangling in arm64's compat handling.

Following the example of ksys_* functions, kcompat_sys_* functions are
intended to be a drop-in replacement for their compat_sys_*
counterparts, with the same calling convention.

This is necessary to enable conversion of arm64's syscall handling to
use pt_regs wrappers.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent bf1c77b4

fs/statfs.c

+12 −2
Original line number Diff line number Diff line
@@ -335,7 +335,7 @@ static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstat 
	return 0;

}



COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)

int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)

{

	struct kstatfs tmp;

	int error;
@@ -349,7 +349,12 @@ COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, s 
	return error;

}



COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)

COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)

{

	return kcompat_sys_statfs64(pathname, sz, buf);

}



int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)

{

	struct kstatfs tmp;

	int error;
@@ -363,6 +368,11 @@ COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct co 
	return error;

}



COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)

{

	return kcompat_sys_fstatfs64(fd, sz, buf);

}



/*

 * This is a copy of sys_ustat, just dealing with a structure layout.

 * Given how simple this syscall is that apporach is more maintainable

include/linux/compat.h

+11 −0
Original line number Diff line number Diff line
@@ -1028,6 +1028,17 @@ static inline struct compat_timeval ns_to_compat_timeval(s64 nsec) 
	return ctv;

}



/*

 * Kernel code should not call compat syscalls (i.e., compat_sys_xyzyyz())

 * directly.  Instead, use one of the functions which work equivalently, such

 * as the kcompat_sys_xyzyyz() functions prototyped below.

 */



int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz,

		     struct compat_statfs64 __user * buf);

int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz,

			  struct compat_statfs64 __user * buf);



#else /* !CONFIG_COMPAT */



#define is_compat_task() (0)

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